A model is proposed to evaluate psychomotor and memory impairment in patients after administration of various intravenous sedation agents. A pilot study has been completed that demonstrated the preciseness and sensitivity of a series of psychomotor and memory tests. Subjects will be volunteers from a Clinic population and from a non-surgical population. Subjects will be tested preoperatively (before drug administration) and then postoperatively at 30 minutes and then hourly for 6 hours. At each evaluation the entire series of memory and psychomotor tests will be administered by a trained research assistant. Six, 7 milliter blood samples will be taken over the six hour evaluation and assayed for parent drug and metabolites in order to correlate plasma concentrations of drug with behavioral effects. Both single entity agents such as diazepam and combination treatments such as diazepam plus meperidine will be evaluated.